I know this is old, but I wanted to add my $0.02 since this is the first thing that comes up on Google when you search for pasteurizing fruit for beer. My wife is gluten intolerant so I've had to play with non-traditional ingredients quite a bit. I've probably now made two dozen beers with raspberries, blackberries, or both raspberries and blackberries.

1) If you want a really fruity flavor, you need to add the fruit in the secondary. I don't want a really fruity flavor. I'm looking for more of a note, not the whole song. The quantity of fruit is as important as when you add the fruit. So I add my fruit at the end of the boil since I'm going for a specific flavor.

2) I have only played with raspberries and blackberries, so I don't know how other fruits react, but what I like to do is:
a) Freeze fresh fruit,
b) When I start the beer I pull the fruit out of the freezer and set it with my other ingredients,
c) I don't boil more than than 2 gal for a 5gal batch (I just don't have the equipment), so when the boil is done, I turn the stove off, and add some water to bring the temp down to 200*,
d) I add the fruit. If I only add a pound it brings the wort down to about 180* (if it doesn't I add more water to get to 180*), which is on the high side but has been fine. If I add more than 1lb it brings the temp down more. I watch the temp to make sure I stay above 160*.
e) I keep the temp between 160-180* for 15min.
f) I then cool and pitch as normal.

I play with sorghum since I brew GF (sorghum makes cloudy beers). But, when I use just rice or do a non-GF brew, my beers come out crystal clear (no pectin haze).

For this past winter I made a (non-GF) milk stout with chocolate (powder and nibs) and 1lb of raspberries and 1lb of blackberries. It was fantastic.

Sorry for bringing back the old post but I've got a question on the topic.

In the next month or so I'm wanting to make a sweet potato beer for the early fall.
I was planning on using a strong brown ale, using spices in the main boil (similar to a pumpkin beer). I was going to add the Sweet Potatoes in the secondary.

Is there anything I need to watch out for (with the starches and what not)? What method should i use in adding the potatoes? I was planning on boiling them be able to mash them.....

Sorry for bringing back the old post but I've got a question on the topic.

In the next month or so I'm wanting to make a sweet potato beer for the early fall.
I was planning on using a strong brown ale, using spices in the main boil (similar to a pumpkin beer). I was going to add the Sweet Potatoes in the secondary.

Is there anything I need to watch out for (with the starches and what not)? What method should i use in adding the potatoes? I was planning on boiling them be able to mash them.....

So I am wondering what you ended up doing? Even though it may be late to respond, but I would think it would be best to almost to have the potatoes already cooked and mashed, and then add the mixture to your boil with the spices and such. My husband is the "head brewer" in our house and I am just the lowly assistant, but he makes a pumpkin beer in a similar fashion (takes canned pumpkin and puts it in the oven for a few then adds to the boil). I really love the way the pumpkin turns out, its by far one of my favorite beers he makes.
I would think doing it this way would give you a nice sweet potato casserole taste after its all done.